Pig Latin is a made-up children's language that's intended to be confusing. It obeys a few simple rules (below), but when it's spoken quickly it's really difficult for non-children (and non-native speakers) to understand.

• Rule 1: If a word begins with a vowel sound, add an "ay" sound to the end of the word.
• Rule 2: If a word begins with a consonant sound, move it to the end of the word, and then add an "ay" sound to the end of the word.

There are a few more rules for edge cases, and there are regional variants too.

See http://en.wikipedia.org/wiki/Pig_latin for more details.